Women who are afraid to give birth have an increased risk of postpartum depression, Finnish researchers say.

In a study of more than 500,000 mothers in Finland, the researchers found women without a history of depression, but who are prenatally diagnosed with a fear of childbirth, are three times more likely to suffer from postpartum depression.

The study found other risk factors, such as caesarean section, pre-term birth and a major congenital anomaly, also increased a woman's risk.

The Canadian Mental Health Association says up to 20% of women experience postpartum depression. Symptoms include feelings of guilt, anxiety and inadequacy, regarding a child with disinterest or negative thoughts, as well as headaches and fatigue. Symptoms can last up to a year, but can be medically treated.